Implantation of phakic intraocular lenses (PIOL) is an artificial lens implanted between the cornea and the normal lens to improve refraction and thus correct myopia. The “implantable collamer lens” (ICL) [1] is a PIOL that is implanted in the posterior chamber and fixed in the ciliary sulcus, in a single-piece posterior arch design that maintains a space between the implanted lens and its own lens, formerly known as ICL (implantable contact lens), but in order to distinguish it from corneal contact lenses, it was renamed as “implantable Collamer lens”, considering that it is made of hydrophilic porcine collagen and hydroxyethyl polymer containing ultraviolet chromophores of Collamer. “ICL has been widely used in clinical practice because of its small surgical incision, wide range of correction, potential reversibility, and less damage to the corneal endothelium. It has been widely carried out in foreign countries, and the number of surgeries in China is rising year by year. I. Study subjects and methods 1. Study subjects: A prospective non-randomized clinical cohort study was used to select 91 patients who underwent implantable collamer refractive lens (ICL) surgery in our department from July 2008 to February 2010 in the posterior chamber of the lens-bearing eye. ICL) in 48 patients with 91 eyes. Among them, 18 were male and 30 were female, with an age range of 19 to 43 years and a mean of 27.8 ± 7.4 years. The age composition of the patients: 31 patients under 30 years old, 14 patients between 30 and 40 years old, and 3 patients over 40 years old; preoperative spherical lens -5.0DS to -23.0DS, mean -12.38DS; corneal thickness 459-621 mm, mean 523 mm; best corrected visual acuity: 0.2-1.2. All patients met the following conditions: corneal transverse diameter ≥11 mm, anterior chamber depth ≥2.8 mm, and normal IOP. 2.8mm, normal intraocular pressure (10-21mmHg), open atrial angle, corneal endothelial cell count >2200 cells/mm2., clear lens, and no active ocular inflammation or other ocular diseases. ICL is calculated by special software and its refraction is determined by the optometry, corneal curvature, anterior chamber depth, and corneal thickness. the length of ICL is determined by the corneal transverse diameter (white-to-white distance), and usually the length of ICL is slightly larger than the corneal transverse diameter to ensure that ICL has a certain arch height (vault), which is the distance between the posterior surface of ICL and the anterior capsule of the lens. 2. Surgical approach: Laser peripheral iridotomy is completed 2 weeks prior to surgery. The location of the peripheral iridotomy is two holes at 10:30 and 1:30 of the iris root in both eyes. The pupil is dilated sufficiently before surgery, a 3.2 mm wide temporal clear corneal incision is made under surface anesthesia, the anterior chamber is injected with viscoelastic, the ICL is implanted into the posterior chamber using a special pusher, the lens is centered, the viscoelastic is rinsed away, and the pupil returns naturally, usually without the use of pupil reduction agents. Postoperative drops of hormone plus antibiotic eye drops for 1 week. 3. Postoperative follow-up: All patients were followed up preoperatively, 1w, 1m, 3m, 6m and 12m postoperatively for uncorrected visual acuity (UCVA), best-corrected visual acuity (BCVA), contrast sensitivity, wavefront aberration, refractive error, central anterior chamber depth, ICL and clear lens gap and corneal endothelial count, and observation of intraocular pressure and lens condition. 4.Inspection instruments and methods: CSV-1000 contrast sensitivity meter from vector-vision, USA was used to detect the contrast sensitivity in natural light and glare. Analyzer (wavelight, erlangen, Germany) was used for aberration examination, and all examinations were performed by the same examiner and repeated three times. 5. Statistical analysis methods: All data were analyzed using SPSS13.0 statistical software. II. RESULTS 1. Patient follow-up rate, 94.5% (86/91) at 1m, 89% (81/91) at 3m, 84.6% (77/91) at 6m, and 71.4% (65/91) at 12m. The mean follow-up time was 9.54±4.12m. 2. Visual acuity:Preoperative BCVA, 90 % over 0.5, 70 % over 0.8, 46 % over 1.0, and 2 % over 1.2. UCVA at 1 week postoperatively was 90% above 0.5, 76% above 0.8, 64% above 1.0, and 24% above 1.2. 58 eyes (64%) had postoperative UCVA of 1.0 and above, and 69 eyes (75.9%) had postoperative BSCVA of 1 line and above compared with preoperative. The relationship between the expected corrected refraction and the actual corrected refraction of the surgery was determined by paired t-test, t=-1.55, p=0.128, and the difference was not statistically significant. Also the difference between refraction and expected corrected refraction at 12 months postoperatively was 93.4% within ±1.0 and 78.6% within ±0.5D. 3. Comparison of contrast sensitivity The paired t-test was used for contrast sensitivity and glare contrast sensitivity before and after surgery. Except for the frequency of 6 cd (p=0.339), there were statistically significant differences in contrast sensitivity and glare contrast sensitivity before and after surgery for 3 cd (p=0.001), 12 cd (p=0.009), and 18 cd (p=0.004). The postoperative contrast sensitivity and glare contrast sensitivity were significantly higher than the preoperative ones, especially in the high frequency part (12-18 cd). 4, wavefront aberration The comparison of the aberration before and after surgery was done by paired t-test. The total aberration zernik root mean square RMS, spherical aberration and coma aberration of the eyes after surgery were significantly reduced compared with those before surgery, and the difference was statistically significant. 5. Follow-up observation of the ICL and clear lens gap (vault) The Petencam 3D anterior segment analysis and diagnosis system analyzes and scans the anterior segment by Scheimpflug imaging technology, which can measure corneal thickness, anterior chamber depth (ACD) and the gap between the ICL and the clear lens (vault). vault). The mean ACD before surgery was 3.17 ± 0.27 mm, and 1 month after surgery the mean ACD was 2.90 ± 0.32 mm, a reduction of 8.52% from the preoperative level. The difference was not statistically significant during the follow-up period after surgery (p=0.562). vault at 6 months after ICL averaged 452±216.38 mm, with a maximum of 1080 mm and a minimum of 130 mm, and the difference was not statistically significant when compared during the follow-up period (p=0.843). 6. Follow-up observation of corneal endothelium, mean corneal endothelial cell density (endothelial cell density , ECD) before surgery: 2862±514 (cells/mm2), mean ECD 1 week after surgery: 2792±492 (cells/mm2), p=0.582, no statistically significant before and after surgery. Mean ECD at 12 months after surgery: 2783±490 (cells/mm2), no statistically significant difference was observed during the follow-up period. 7. Surgical complications: All surgeries were successful, and there was no case of termination of surgery or removal of ICL due to complications such as pupillary block or cataract during surgery. Two eyes (2.1%) had a significantly shallower anterior chamber (31% lower) than before surgery; 13 eyes (14.3%) had a transient IOP increase at the 1-week follow-up. Discussion: Many studies have shown that ICL implantation is effective in correcting myopia and has the advantages of stability, reversibility, and ease of operation [1]. In this study, the surgeries were successful, and none of the cases were terminated or the ICL was removed because of pupillary block or cataract during surgery. And all operated patients had improved postoperative visual acuity and patient satisfaction. In the 91 eyes that we operated, 64% of the post-operative UCVAs reached 1.0 or higher, and all BSVAs reached and exceeded the pre-operative level, with a 76.9% increase of 1 line or more from the pre-operative level. In patients with ultra-high myopia (-15.0D or higher), the BSVA after surgery far exceeded the preoperative one, with 96% (54/56) exceeding the preoperative two rows, which is related to the adequate correction of refractive error and the elimination of the reduction of the object image by the frame glasses [2]. Our refractive correction was observed and the difference from the expected corrected refraction within ±1.0 was 93.4% and within ±0.5 D was 78.6% at the last follow-up time.The correction range for ICL is -20.0 D diopter, and in our study 9 eyes (9.9%) best corrected spherical lenses over -20.0 D while combined with column lenses over -2.0 D. At the time of surgical design However, the postoperative UCVA in these patients reached and exceeded the preoperative BCVA (see Figure 3). At the same time, the actual refractive error corrected by the surgery basically met the surgical expectation, and the refractive error was stable during the patient’s follow-up observation, which was better than that reported by foreign scholars [3]. Visual quality is also a concern after ICL surgery. The visual quality of patients after excimer laser surgery can be reduced to varying degrees, mainly in terms of contrast sensitivity and glare contrast sensitivity compared to the preoperative period, especially for patients with high myopia [6]. Many reports have confirmed that the visual quality after ICL is superior to that of excimer laser surgery [4].Akihito et al. compared the contrast sensitivity before and after ICL surgery and found that the contrast sensitivity in the high-frequency region increased significantly after ICL [7]. In our study, the level of contrast sensitivity curve increased after surgery basically close to the normal range. Also glare sensitivity increased significantly compared to the preoperative period, which is related to the fact that the majority of patients undergoing ICL surgery are super high myopic and require a relatively small optical area, while the surgery does not alter the optical plane of the cornea and does not have the inflammatory and proliferative effects of the tissue after excimer laser surgery. Another factor that affects the quality of vision after surgery is higher-order aberrations, and the RMS values representing higher-order aberrations in our results were significantly reduced after surgery.